Category Archives: Water

Dry

oct-2016-drought

…from the US Drought Monitor. They state that parts of the southeast “recorded their driest 60-day periods on record.” Walking in the woods confirms the map’s testimony: blueberries, hollies, mountain laurel, hickories — all shriveled and crisped. To see these drought-adapted plants pushed beyond their limits is astonishing. Hopefully they got enough invested into their buds in summertime that they’ll be able to try again next year, but it seems that many may succumb.

The map also shows drought over parts of California, a familiar pattern now. Compared to this time last year, the “exceptional” drought area is slightly smaller. Conditions have been so dry in the western US that the “missing” water from dry soil has caused that side of the continent to weigh less (by 240 gigatons in 2014), resulting in a crustal rebound of up to 5mm. Drought with geologic consequences.

So here’s the obligatory cracked-mud cliché photo. For those familiar with Sewanee: this is the Lake Cheston “beach” area.

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Merrymeeting

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At the confluence of six rivers and a long tidal inlet: 9000 acres of part-salted water and mud known as the Merrymeeting Bay. Forty percent of Maine’s freshwater flows to the Gulf of Maine through this inland delta. The Gulf’s waters surge into bay twice daily, pushed by oceanic tidal forces but slowed by their long passage through the rock cleft that is the lower Kennebec River. High tide here is hours later than on the coast.

For decades, the waters were so polluted that paint would peel from any building located near the bay or its upstream rivers. Great rafts of dead fish flowed out with the tides. The stink worked its ways into the growth pattern of towns. Apart from huge brick-walled mills — now shuttered or turned to self-storage units — towns and farms turned their backs on the river and bay. Only the poorest parts of town had water views. Unlike the southern Maine seacoast that is now largely encrusted with expensive houses, shores here comprise rock, poisoned mud, and a few scattered hunting lodges. This leaves room for others: Eagles are common, although their bodies are spiced with the toxic remnants of upstream industries. Signs warn humans not to consume the fish, but eagles don’t give a damn about what they read. The flow of some chemical effluent is now diverted into other rivers, other bodies, in other lands. Outsourced, to benefit America’s waters and retail outlets.

Wild rice grows in abundance on the mudflats. In late summer bobolinks flee the mown inland meadows to feast in the rice thickets and roost. Now, at the equinox, the bobolinks are winging away to try their luck in a southern continent. Ducks gather in their place to dabble at rice and aquatic insects. Below the water, endangered short-nosed and Atlantic sturgeon swim slowly upstream, nosing through a vestige.

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High water: Buggytop cave.

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Last week brought seemingly never-ending rainstorms to Sewanee. The downstream effects were dramatic. Crow Creek, running from the entrance to Buggytop Cave, south of Sewanee, was overtopping huge boulders and engulfing trees.

The water here comes from the sinkhole in Lost Cove and from the many streams that run from the south side of Sewanee. The water’s brown tinge is a melange of woodland tannins, soil erosion, and whatever washes from the streets and houses of exurbia.

Inside the cave entrance, the water’s sounds echoed from walls and the low ceiling. Quite a thunder.

(to hear sound, email subscribers need to click on the post’s title to link to the webpage)

The Buggytop cave entrance is a wide maw, easily walkable when the water is low. One hundred or more feet of limestone cliff extend above the entrance. The cave goes back about a mile into the limestone. According to Gerald Smith and Sean Suarez’s ever-fascinating Sewanee Places, the cave gets its name from the folded appearance of the collapsed rocks inside the entrance. Coincidentally, an abandoned buggy trail from Sherwood into Lost Cove passes not far from the cave entrance. Smith and Suarez also relate that the cave’s accessibility and popularity make it the number one site for local cave rescues. Many a poorly-equipped wanderer has become disoriented after their lights fail, both inside the cave and on the sinuous trail from the road. I was not tempted to join the list of rescuees by attempting a solo passage through the whomping water. Sitting in the presence of the echoing tumult was excitement enough.

Crash, hop. Inscriptions on flakes.

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The motions of a landing, wing-folding, strutting, tip-toeing, recorded on an icy pond. Most likely a sparrow.

Snow scribing. Here are the plants at work, from last year.

Jericho

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The city of Jericho is most famous for the unkind things that Joshua is reputed to have done to Jericho’s populace after God gave him the nod to move in. But Jericho’s history is far more complicated than the Biblical story. Jericho is likely the oldest continually inhabited city in the world and archaeologists have unearthed more than twenty distinct physical “layers” of remains, evidence of dozens of city cultures that waxed and waned over ten thousand years. Old stone tools show that before the cities, hunter-gatherers lived in the region, extending human habitation of the region back another thousand years or so.

All this history literally heaped upon itself and built a hill, Tell es-Sultan, a mound that seems like a natural dome, but is in fact built entirely from the accumulated stone and sand of these cultures accreting on the remains of their predecessors.

The photograph above looks down about twenty meters into a trench that has exposed walls that date to 8000 BCE. At that time Jericho was already a fortified city. People appear to have lived in and around ever since. Why? Water. The Ain es-Sultan spring runs year-round and has given life to Jericho for thousands of years, supporting agriculture in a landscape that is otherwise astoundingly dry for much of the year. The spring is sometimes called “Elisha Spring,” for the prophet who we’re told sweetened its waters. The archaeological evidence, though, suggests that the water was good before Elisha wandered past.

The fountain above uses a small portion of the water from the spring, the main outflow is contained within a building a few steps from here. The dragonflies that visit are separated from their kin by many, many miles. And because Jericho sits more than two hundred meters below sea level, these may be the lowest dragonflies on the planet:

Joshua was hardly the last person to clear a city in God’s name (although Jerusalem must surely beat Jericho in the league table of crusades and other bids for the “promised” land). After Israel’s declaration of independence in 1948, a portion of the seven hundred thousand refugees from the newly formed state moved to a camp in Jericho. In the 1967 war, many of these refugees relocated to Jordan, so the Jericho camp is one of the smaller remaining refugee camps.

Jericho has also been the site of violent attacks from both sides in the ongoing conflict over the West Bank. The city is currently run by the Palestinian Authority, under the eye of the Israeli army (who carry guns called “Jericho 941“). An Israeli army post sits just outside the city. During my brief visit, Palestinian men were lined up outside, summoned by the Israeli military for interviews.

Tell es-Sultan has yet to see the end of layers upon layers.

Young vertebrates enjoying the South Platte River in Colorado

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High in the mountains, in Eleven Mile Canyon:

A Common Merganser with her brood. She incubated the chicks in an old woodpecker hole and will stay with them as they learn to forage. These “sawtooth” ducks dive under the water to snatch fish. They’ll also feed on invertebrates such as snails and mayflies.

American Dipper fledgling. This young bird left the nest a week or so ago. It waits for the parent to appear…

…from beneath the fast-flowing water. Dippers dive into mountain streams and walk along the bottom, gripping with their toe-nails for all they’re worth, plucking stream insects from rocks. Once emerged, the adult is met with the youngster’s loud whistles, sounds that cut through the roar of the water. When food is stuffed into the gullet of the noisy birdchild, the sound changes to delighted chirping.

And when the feeding is done, it is time for more piercing begging cries, delivered at the water, below which the parent feeds.

Another gullet-stuff, another flurry of chirps:

Downstream, in the heart of Denver:

At Confluence Park, in the center of the city, the South Platte has been engineered to provide a series of chutes and rapids for the amusement of Denverites. In the photo below a youth leader takes one of several disabled kids on a paddle ride down the rapids. I’ve blanked the faces because I was not able to ask whether it was OK to post these two water-lovers’ faces on my blog (sorry, dippers and mergansers, speciesism…). As he lurched through the spray, the kid’s face went from apprehensive frown, to a big O of surprise, to a grin of delight. A (mile-)high-five ended the ride.

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In the 1960s and 1970s, this stretch of river was the most junky, polluted part of the whole city. Old cars, tires, and mattresses were heaped along the banks; factories piped effluent directly into the river; oil oozed from every bank. Thanks to the very hard work of the Greenway Foundation, The City of Denver, and many other partners, this is one of the most popular places in town for people of all races, incomes, and levels of physical ability. One hundred miles of riverside trails radiate out from here, punctuated with parks of all kinds.

The river flows onward from here, east through Colorado and Nebraska, hopefully encountering a few more young lifeforms reveling in its waters.

Quicksilver

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After heavy rain, water turns mercurial on nasturtium leaves. The water balls into a skittering drop, seeming to float just over the leaf’s surface. I was reminded of chasing liquid metal over chemistry lab benches in the days before kids were protected from such amusements. But similar delights, minus the metabolic cost, await in the garden.

The drops were dancing. Water on the leaves of other plants was sluggish, gathering in flat pools or damp stains. These plants were wet, soggy, but the nasturtium leaves were perfectly dry, even where silvery drops had sat a few seconds before.

A recent paper by James Bird and colleagues in Nature reported that nasturtium leaves are covered with “superhydrophobic ridges” (literally, “super-water-fearing ridges”). These minute structures on the leaf surface exert a strong repulsive force on water. When a water drop hits the surface, the repulsion is so strong that the drop recoils, shatters into minute droplets, and jumps back into the air. The Nature paper does not mention this, but my observations suggest that nasturtium leaves only shed large drops. On dewy mornings, smaller drops manage to cling, although they still sit as silvery globes.

Leaves of almost all land plants have a waxy covering that keeps water away from the core of the leaf and eventually causes water to run off. But on nasturtium leaves, water doesn’t just run, it springs and sprints. Nasturtium beats even the former superchampion of “hydrophobicity,” the water-shedding upper surface of lotus leaves. What function might this serve? We do not know, but shedding water must surely combat fungal infections by depriving spores of damp places in which to germinate.

All this makes for ephemeral beauty in the garden. It may also be of practical importance. Surfaces that vigorously repel water not only stay remarkably dry, but they self-clean and resist icing. Engineers would love to incorporate these features into all kinds of surfaces, especially cloth, windows, painted walls, airplane wings, and the insides of ketchup bottles (the BBC has a nice overview).

I look forward to venturing into the woods clad in a coat of nasturtium, a fig leaf for rainy climes.

Listen: underwater crackly, groany kōans

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Drop a hydrophone into shallow salt water at latitudes less than 40° and you’re likely to hear a crackling sound, sometimes so loud that it drowns out almost all other underwater sounds. This din is created by snapping shrimp, tiny crustaceans that click one of their front claws so fast that the motion creates a bubble of air, a cavitation in the water. The rapid opening and closing of the bubble generates sounds as loud as 200 dB (as loud or louder than dolphins and whales) and very briefly heats the bubble to a temperature just shy of that on the surface of the sun. Understandably, nearby prey are stunned, as was I when I read these figures. The shrimp also use their loud, hot snaps to wrangle over territories and to attract mates.

Here are the sounds of these creatures recorded from the dock at St Catherine’s Island (if you’re an email subscriber or viewing on a phone, you might need to click on the header link to go to the website to get sounds…):

In some tropical sponge-dwelling snapping shrimp “a sentinel shrimp reacts to danger by recruiting other colony members to snap in concert for several to tens of seconds” (Tóth and Duffy 2005). So these shrimp are somewhat like crows, honeybees, and other social creatures: networking information through their societies.

Another sound from the dock, heard amid the shrimp (I filtered out many of the high frequencies to make the sound a little easier to hear):

This is the territorial call and the mating cry of a toadfish. These ogre-like creatures sit under rocks or in crevices the bottom of the seafloor, waiting to ambush smaller fish and other morsels. The Billy Goat Gruff of the seas. Their mouths are liked toothed baseball mitts.

Despite its unappealing visage, the toadfish has much to recommend it to the curious naturalist. The call is produced by vibratory muscles attached to the swim-bladder (bagpipes?). These muscles are the fastest known among all vertebrates. Once mating is done, the male toadfish defends the eggs, then guards the hatchlings until they find their own bridge to hide under.

NASA once sent toadfish into space. According to Wikipedia, they found that toadfish inner ear bones developed in the same way in orbit as back here on planet Earth. Good to know. This study also answers the kōan,

Can a toadfish in space orbit be said to be under his rock?

But poses a new one,

If a toadfish vibrates his swim bladder in the vacuum of space, is he singing? And, for extra kōa-credit, who might answer his airless call?

For now, toadfish are hiding under their rocks with even greater diligence, fearing capture for space experiments, waiting for Homo sapiens to pass on by. Here is the sound of our departure from the dock, heard from the toadfish’s watery home:

Many thanks to Dr John Schacke from UGA and the Georgia Dolphin Ecology Program who helped me to understand what I was hearing.

Washed up

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The students in the Sewanee Island Ecology Program have repeated the studies that I began last year of “trash” on the beaches of St Catherine’s Island, GA. We search standardized transect lines in the wrack on the upper beach.

If our samples are representative of the whole beach, and assuming a 20 meter wide wrack line, a 10 km stretch of beach would have just shy of half a million individual pieces of anthropogenic debris. Foam pieces are the most common (80% of pieces), followed by other plastics. Half of all debris pieces were 2cm wide or smaller. These data only include pieces of debris that are visible on the surface. Much more is likely buried deeper. We did not examine microscopic fragments.

Here are some photos of some of the items we found.

Brut. Advertized on their websites as the “Essence of Man.” Indeed. This one washed up from …somewhere… as we were walking our transects.

Epibionts on plastic bottle. Darwin would be proud. It’s all about barnacles.

Still life with pill bottle.

Just what the ocean needs, a little more engine oil. Probably drilled from under the ocean. Sustainability is all about closing the circle…

I also made some sound recordings along the beach. The first is made with a hydrophone, a microphone that picks up sounds below the surface of the water. I suspended it in some gentle surf. The second recording is the same surf, but recorded with a regular microphone, in the air, at the top of the beach.

Toads, Saint Patrick, and biogeography

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Warm the soil, add an inch or two of rain. The result: toads. Defrosted and ready to grasp springtime’s possibilities.

As I write, I hear one trilling in the pond outside. Hopefully the next weeks will bring dozens more. Toad song after a long, long winter is melodious glory.

Thanks to St Patrick (on whose feast day I’m posting this), the Irish don’t get to delight in the sounds of Bufo bufo, the common European toad. Apparently Patrick kicked them out along with the snakes. It is a herpeto-theological mystery why the saint chose not to preemptively bar more pestiferous species — biting flies, fungal blights, or the English — instead of the humble toad. His work was incomplete, though: the rarer natterjack toad has a toe-hold in a few parts of Ireland.

These tales of missing species from islands point at an important area of study in biology, namely the curious fauna and flora of isolated land masses. The technical term is “disharmonious.” Islands have communities that contain some, but not all, of the species of nearby continents (the islands are therefore out of “harmony”). The more distant the island, the more peculiar the biological community, all a result of the unlikelihood of colonization. Ireland is missing just a few European species. In contrast, the Galapagos islands sit far out to sea and are missing most of the species of mainland South America. Indeed, so few colonists have made it to these outposts that in situ evolution has provided much of the local diversity. The same is true of the Hawaiian islands and other oceanic isolates.

This disharmony is hard to explain from a creationist perspective, so it is no accident that islands feature prominently in the thinking and writing of the originators of the theory of natural biological evolution, Darwin and Wallace. To them, the idea that the distribution of animals and plants is explained by the particularities of historical accident seemed a more fruitful hypothesis than de novo creation.

Now of course, we’re erasing all this isolation with our planes and ships. Our mobility is undoing St Patrick’s work, homogenizing the world, sometimes with regrettable consequences: here is a list of the non-native species currently threatening Ireland’s biodiversity. More saints needed?